/*
Copyright 2006 Jerry Huxtable

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
 */

/*
 * This file was semi-automatically converted from the public-domain USGS PROJ source.
 */
package geovista.projection;

import java.awt.geom.Point2D;

import geovista.projection.units.MapMath;
import geovista.projection.units.ProjectionException;

public class RobinsonProjection extends PseudoCylindricalProjection {
	final static double X[] = { 1, -5.67239e-12, -7.15511e-05, 3.11028e-06,
			0.9986, -0.000482241, -2.4897e-05, -1.33094e-06, 0.9954,
			-0.000831031, -4.4861e-05, -9.86588e-07, 0.99, -0.00135363,
			-5.96598e-05, 3.67749e-06, 0.9822, -0.00167442, -4.4975e-06,
			-5.72394e-06, 0.973, -0.00214869, -9.03565e-05, 1.88767e-08, 0.96,
			-0.00305084, -9.00732e-05, 1.64869e-06, 0.9427, -0.00382792,
			-6.53428e-05, -2.61493e-06, 0.9216, -0.00467747, -0.000104566,
			4.8122e-06, 0.8962, -0.00536222, -3.23834e-05, -5.43445e-06,
			0.8679, -0.00609364, -0.0001139, 3.32521e-06, 0.835, -0.00698325,
			-6.40219e-05, 9.34582e-07, 0.7986, -0.00755337, -5.00038e-05,
			9.35532e-07, 0.7597, -0.00798325, -3.59716e-05, -2.27604e-06,
			0.7186, -0.00851366, -7.0112e-05, -8.63072e-06, 0.6732,
			-0.00986209, -0.000199572, 1.91978e-05, 0.6213, -0.010418,
			8.83948e-05, 6.24031e-06, 0.5722, -0.00906601, 0.000181999,
			6.24033e-06, 0.5322, 0., 0., 0. };

	private final static double Y[] = { 0, 0.0124, 3.72529e-10, 1.15484e-09,
			0.062, 0.0124001, 1.76951e-08, -5.92321e-09, 0.124, 0.0123998,
			-7.09668e-08, 2.25753e-08, 0.186, 0.0124008, 2.66917e-07,
			-8.44523e-08, 0.248, 0.0123971, -9.99682e-07, 3.15569e-07, 0.31,
			0.0124108, 3.73349e-06, -1.1779e-06, 0.372, 0.0123598, -1.3935e-05,
			4.39588e-06, 0.434, 0.0125501, 5.20034e-05, -1.00051e-05, 0.4968,
			0.0123198, -9.80735e-05, 9.22397e-06, 0.5571, 0.0120308,
			4.02857e-05, -5.2901e-06, 0.6176, 0.0120369, -3.90662e-05,
			7.36117e-07, 0.6769, 0.0117015, -2.80246e-05, -8.54283e-07, 0.7346,
			0.0113572, -4.08389e-05, -5.18524e-07, 0.7903, 0.0109099,
			-4.86169e-05, -1.0718e-06, 0.8435, 0.0103433, -6.46934e-05,
			5.36384e-09, 0.8936, 0.00969679, -6.46129e-05, -8.54894e-06,
			0.9394, 0.00840949, -0.000192847, -4.21023e-06, 0.9761, 0.00616525,
			-0.000256001, -4.21021e-06, 1., 0., 0., 0 };

	private final int NODES = 18;
	private final static double FXC = 0.8487;
	private final static double FYC = 1.3523;
	private final static double C1 = 11.45915590261646417544;
	private final static double RC1 = 0.08726646259971647884;
	// private final static double ONEEPS = 1.000001;
	private final static double EPS = 1e-8;

	public RobinsonProjection() {
	}

	private double poly(double[] array, int offset, double z) {
		return (array[offset] + z
				* (array[offset + 1] + z
						* (array[offset + 2] + z * array[offset + 3])));
	}

	@Override
	public Point2D.Double project(double lplam, double lpphi, Point2D.Double xy) {
		double phi = Math.abs(lpphi);
		int i = (int) Math.floor(phi * C1);
		if (i >= NODES) {
			i = NODES - 1;
		}
		phi = Math.toDegrees(phi - RC1 * i);
		i *= 4;
		xy.x = poly(X, i, phi) * FXC * lplam;
		xy.y = poly(Y, i, phi) * FYC;
		if (lpphi < 0.0) {
			xy.y = -xy.y;
		}
		return xy;
	}

	@Override
	public Point2D.Double projectInverse(double x, double y, Point2D.Double lp) {
		int i;
		double t, t1;

		lp.x = x / FXC;
		lp.y = Math.abs(y / FYC);
		if (lp.y >= 1.0) {
			if (lp.y > 1.000001) {
				throw new ProjectionException();
			}
			lp.y = y < 0. ? -MapMath.HALFPI : MapMath.HALFPI;
			lp.x /= X[4 * NODES];
		} else {
			for (i = 4 * (int) Math.floor(lp.y * NODES);;) {
				if (Y[i] > lp.y) {
					i -= 4;
				} else if (Y[i + 4] <= lp.y) {
					i += 4;
				} else {
					break;
				}
			}
			t = 5. * (lp.y - Y[i]) / (Y[i + 4] - Y[i]);
			double Tc0 = Y[i];
			double Tc1 = Y[i + 1];
			double Tc2 = Y[i + 2];
			double Tc3 = Y[i + 3];
			t = 5. * (lp.y - Tc0) / (Y[i + 1] - Tc0);
			Tc0 -= lp.y;
			for (;;) { // Newton-Raphson
				t -= t1 = (Tc0 + t * (Tc1 + t * (Tc2 + t * Tc3)))
						/ (Tc1 + t * (Tc2 + Tc2 + t * 3. * Tc3));
				if (Math.abs(t1) < EPS) {
					break;
				}
			}
			lp.y = Math.toRadians(5 * i + t);
			if (y < 0.) {
				lp.y = -lp.y;
			}
			lp.x /= poly(X, i, t);
		}
		return lp;
	}

	@Override
	public boolean hasInverse() {
		return true;
	}

	@Override
	public String toString() {
		return "Robinson";
	}

}
